Work accommodations

Has anyone requested an extra day of wfh due to their autism, my pyschtriast who diagnosed me offered to write me a note for it and heavily implied I should at least ask for accommodations. I'm at a new job though and I don't really want to give them an excuse to discriminate against me... I was thinking 3 days remote 2 days in office. Current policy is 3 days in office, 2 remote.

I'm also not crazy about having to tell HR I'm autistic, is there a way around that. What is everyone's experience?